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# What is a Qredit Address?

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• What is a Qredit Address?

## Foreword

Cryptography behind blockchain technology

Public-key or asymmetric cryptography, is an encryption scheme that uses a public key and a private key. The public key is used to encrypt and the private key is used to decrypt.

A blockchain account is defined by its address that is derived from a public key. It allows everyone to verify that data is signed by the corresponding private key. This signature acts as proof of ownership.

It is impossible to compute the private key from the public key. Because of this, public keys can be freely shared, allowing users an easy and convenient method for encrypting content and verifying digital signatures, and private keys can be kept secret, ensuring only the owners of the private keys can decrypt content and create digital signatures [1].

Qredit uses the SECP256k1 curve from the elliptic curve digital signature algorithm (ECDSA).

ECDSA generates the private key and the public key pair from a unique 32-bytes-size seed. As the seeds are not very human readable, we have the option to generate the seed from something more convenient : a passphrase.

The passphrase is a written in simple readable text. It often consists of twelve words according to the Bitcoin Improvement Protocol #39 (BIP39). The usage of the protocol is not mandatory as a seed can be generated from any kind text, but is recommended. A passphrase needs enough complexity and has to be random enough in order to be considered secure.

From a passphrase to private and public keys

passphrase simple secret
seed b6af972cfcff450addadfecccc1d222de0f28c92c349a6bcbba4d4267dd3199c
public key 036f9f2b56926a8c28c3bcef02811b6b3338c4d67b06eb7a9e90bda0fb3eacedee
private key 9b449f2ac4525b0116c7a78ce52387aab2ad6d928749cd26e60f2588efc5c01d
address AJZkkwhCjDG5AS9gZcNfKzTa3s1qwvD44r

A blockchain is a distributed database where records are stored according to a consensus mechanism (secure protocol) executed by a network of nodes (Peer-To-Peer network). The unitary element used in this process is an account to account transaction containing information such as senderIdrecipientIdamount and fee. A sender and recipient account needs to be identifiable. This is enabled by using an address and information related to token balance and transaction history are linked to it.

The Qredit address is like a bank account where only the owner of the private key can validate and broadcast transactions. It is very important to keep the passphrase safe.

From a public key to a Qredit address

A modifier is a byte used to customize the address. It is useful to differentiate networks :

• On Ark mainnet modifier = 0x3A so Ark address starts with Q
• On Ark devnet modifier = 0x4B so DArk address starts with X

Here is the table giving the address start char according to hexadecimal modifier value :

hex start char hex start char hex start char hex start char hex start char
00 1 10 7 20 D or E 30 L 40 S or T
01 Q or o 11 7 or 8 21 E 31 L or M 41 T
02 o or 2 12 8 22 E or F 32 M 42 T
03 2 13 8 or 9 23 F 33 M 43 T or U
04 2 or 3 14 9 24 F 34 M or N 44 U
05 3 15 9 25 F or G 35 N 45 U or V
06 3 16 9 or A 26 G 36 N or P 46 V
07 3 or 4 17 A 27 G or H 37 P 47 V
08 4 18 A or B 28 H 38 P 48 V or W
09 4 or 5 19 B 29 H 39 P or Q 49 W
0a 5 1a B 2a H or J 3a Q 4a W or X
0b 5 1b B or C 2b J 3b Q or R 4b X
0c 5 or 6 1c C 2c J or K 3c R 4c X
0d 6 1d C or D 2d K 3d R 4d X or Y
0e 6 or 7 1e D 2e K 3e R or S 4e Y
0f 7 1f D 2f K or L 3f S 4f Y or Z
hex start char hex start char hex start char hex start char hex start char
50 Z 60 f or g 70 n 80 t 90 z or 2
51 Z 61 g 71 n 81 t or u ≥91 2
52 Z or a 62 g 72 n or o 82 u
53 a 63 g or h 73 o 83 u or v
54 a or b 64 h 74 o or p 84 v
55 b 65 h or i 75 p 85 v
56 b or c 66 i 76 p 86 v or w
57 c 67 i 77 p or q 87 w
58 c 68 i or j 78 q 88 w or x
59 c or d 69 j 79 q or r 89 x
5a d 6a j or k 7a r 8a x
5b d or e 6b k 7b r 8b x or y
5c e 6c k 7c r or s 8c y
5d e 6d k or m 7d s 8d y or z
5e e or f 6e m 7e s or t 8e z
5f f 6f m or n 7f t 8f z

## Ledger Nano S

The best way to secure Qredit address is to use a device that can sign transactions off the network. The Qredit team developed an application running on Ledger Nano S hardware wallet allowing such a security.

The Ledger Nano S device does not store tokens. It is a device that generates public and private keys from a master seed. Keys are issued from the seed using the derivation path. For Qredit blockchain (and cloned ones) the derivation path is structured like this :

44'\111'\<account index>'\0\<address number>

So the derivation path of address #1 from account #1 is :

44'\111'\0'\0\0